[MD] Adjust algorithm for colorizing icons in incognito contexts.

ui/gfx/color_utils.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/color_utils.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 310 matching lines @@
 }
 
 // OS_WIN implementation lives in sys_color_change_listener.cc
 #if !defined(OS_WIN)
 bool IsInvertedColorScheme() {
   return false;
 }
 #endif  // !defined(OS_WIN)
 
 SkColor DeriveDefaultIconColor(SkColor text_color) {
-  // This function works similarly to BlendTowardOppositeLuminance, but uses a
-  // different blend value for lightening and darkening.
+  // Lighten a dark color but leave it fully opaque.
   if (IsDark(text_color)) {
     // For black text, this comes out to kChromeIconGrey.
     return color_utils::AlphaBlend(SK_ColorWHITE, text_color,
                                    SkColorGetR(gfx::kChromeIconGrey));
   }
-  // The dimming is less dramatic when darkening a light color.
-  return color_utils::AlphaBlend(SK_ColorBLACK, text_color, 0x33);
+  // For a light color, just set an opacity.
+  return SkColorSetA(text_color, 0xCC);

[sky, 2016/05/13 19:29:34]

Might test_color have an alpha < 0xCC?

[Evan Stade, 2016/05/13 21:20:44]

yea, I guess text color can be non-opaque (theme-controlled text as on the
bookmark bar being the only example I can find), so this should actually be a
multiplication.

 }
 
 }  // namespace color_utils